1. Field of the Invention
The present invention relates to a power transmission line dip measurement method, and more particularly to a power transmission line dip measurement method that is capable of easily and accurately constructing a power cable based on a designed dip during the construction of the power line at power transmission steel towers and, in addition, of accurately measuring a dip of an already constructed power line.
2. Description of the Related Art
Generally, the shortest straight distance between a straight line linking power line support positions of two power transmission steel towers and a vertex of a power line is referred to as a power line dip D. The vertex is the lowest point of a curve formed by the power line when the power line is connected to the power line support positions of the power transmission steel towers.
A conventional power line dip measurement method is an indirect type measurement method in which two workers individually climb two steel towers that support a power line and observe a tangent of the power line using a dip chuck and an observation mirror over a predetermined length of the power line to calculate the maximum magnitude of a dip in a measurement section.
In order to measure the power line dip D, the height between the power line support points and the tangent is actually measured at the steel towers, an observation point and a dip chuck installation points are set, and the power line is observed using an observation instrument, such as the observation mirror, such that the tangent of the power line coincides with an observation line.
In the indirect type power line dip measurement using the tangent of the power line, however, all the processes are carried out on the steel towers, with the result that errors may be increased. In addition, the maintenance of accuracy is difficult due to the slope of the steel towers and complicated structure of the steel towers, with the result that measurement errors may be increased.
Also, the workers must climb up several positions of the steel towers according to the positions of power lines, with the result that it is difficult to secure the safety of the workers, and therefore, the workers may be exposed to danger. In addition, power line dip measurement time is increased, and the number of necessary workers is increased.
Also, it is difficult to perform accurate power line dip measurement and maintain the dip of the constructed power line for each phase and for each conductor. Furthermore, the dip difference between conductors may cause short circuits of wires.